Datasheet

High Fuse Byte Bit No. Description Default Value
EESAVE 3 EEPROM memory is preserved through
the Chip Erase
1 (unprogrammed), EEPROM not
reserved
BOOTSZ1 2 Select Boot Size
(see ATmega8A Boot Loader
Parameters)
0 (programmed)
(3)
BOOTSZ0 1 Select Boot Size
(see ATmega8A Boot Loader
Parameters)
0 (programmed)
(3)
BOOTRST 0 Select Reset Vector 1 (unprogrammed)
Note: 
1. The SPIEN Fuse is not accessible in Serial Programming mode.
2. The CKOPT Fuse functionality depends on the setting of the CKSEL bits, see Clock Sources for
details.
3. The default value of BOOTSZ1:0 results in maximum Boot Size. See Boot Loader Parameters for
details.
4. When programming the RSTDISBL Fuse Parallel Programming has to be used to change fuses or
perform further programming.
Table 29-4. Fuse Low Byte
Low Fuse Byte Bit No. Description Default Value
BODLEVEL 7 Brown out detector trigger level 1 (unprogrammed)
BODEN 6 Brown out detector enable 1 (unprogrammed, BOD disabled)
SUT1 5 Select start-up time 1 (unprogrammed)
(1)
SUT0 4 Select start-up time 0 (programmed)
(1)
CKSEL3 3 Select Clock source 0 (programmed)
(2)
CKSEL2 2 Select Clock source 0 (programmed)
(2)
CKSEL1 1 Select Clock source 0 (programmed)
(2)
CKSEL0 0 Select Clock source 1 (unprogrammed)
(2)
Note: 
1. The default value of SUT1:0 results in maximum start-up time. See table Start-up Times for the
Internal Calibrated RC Oscillator Clock Selection in Calibrated Internal RC Oscillator of the System
Clock and Clock Options chapter for details.
2. The default setting of CKSEL3:0 results in internal RC Oscillator @ 1MHz. See table Internal
Calibrated RC Oscillator Operating Modes in Calibrated Internal RC Oscillator of the System Clock
and Clock Options chapter for details.
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1
(LB1) is programmed. Program the Fuse bits before programming the Lock bits.
Related Links
AVR 8-Bit Microcontroller
MEMPROG- Memory Programming
© 2017 Microchip Technology Inc.
Datasheet Complete
40001974A-page 290